1. Field of the Invention
This invention relates to a controller, and more particularly to an improved device such as a programmable controller suitable for a sequence control.
2. Discussion of the Related Art
There is well known a controller or a sequence control system employing a programmable controller, in which a communication unit as a master station is mounted to a base unit of the programmable controller, terminals as a plurality of slave stations are connected to the communication unit, and each of the terminals is connected by an input unit such as a limit switch or various sensor or an output unit such as a air valve or an actuator. In such a well known sequence control system, ON-OFF input data produced from the input unit such as the limit switch or various sensor is transferred to the programmable controller through the terminals, the programmable controller receives the input data to operate the received data in accordance with a program set beforehand and generate ON-OFF output data to be applied to the output unit such as the air valve or actuator through the terminals, and a machine tool is thus controlled.
The conventional programmable controller is provided with a connector connection unit to be connected with a programming tool, RS232 association components device or the like. When a cable connector of the programming tool is mounted on the connector connection unit, the cable connector is kept to externally project from a main housing body of the programmable controller. That is, the cable connector mounted on the main housing body of about rectangular parallelepiped is kept to eternally project bringing a dead space by the wiring. In the sequence control system, the base unit of the programmable controller is mounted by the communication unit employing a communication CPU whereby an input-and-output response time is delayed because data transmission is delayed between the CPU of the base unit and the communication CPU of the communication unit. The base unit of the programmable controller and the communication unit are separated units, so that an interface circuit or the like is necessary to be disposed between the both units and each unit has to be provided with CPU, resulting into a bulky configuration and expensive controller.